1. Field of Invention
The present invention relates to a centralized power distribution unit for a vehicular thin brushless motor.
2. Description of Related Art
Recently, automobiles with good fuel economy have been in high demand. As one example of automobile manufacturers' efforts to meet these demands, hybrid cars with super low fuel consumption have been developed. In particular, a hybrid car has been proposed recently which is provided with an auxiliary power mechanism (a motor assist mechanism) in which an engine provides the main power and a DC brushless motor assists the engine upon acceleration or the like.
The motor assist mechanism is subject to much constraint in installation, since a brushless motor constituting the motor assist mechanism is disposed in a limited space, for example, a space between an engine and a transmission in an engine compartment. Thus, such a brushless motor is required to have a thin configuration.
A thin brushless motor to be used in the motor assist mechanism of a vehicle includes a rotor directly connected to a crankshaft of the engine, and a ring-like stator enclosing the rotor. The stator includes many magnetic poles that have windings on cores, a stator holder that contains the magnetic poles, and a centralized distribution unit that concentratedly distributes currents to the windings.
Conventionally, when a centralized power distribution unit for a vehicular thin brushless motor is to be produced, bus bars for three phases, such as the U-, V-, and W-phases, are separately stamped out into a ring-like shape by using different presses.
Since a very large current flows through a motor of this type, a centralized power distribution unit which is used in such a motor is requested to have considerably high dielectric strength. In order to ensure an insulation distance, therefore, bus bars which are disposed correspondingly with the motor phases must be separated from one another by a predetermined gap in a resin insulation layer.